Combination antiretroviral therapy can control HIV-1 replication and delay disease progression. However, despite the complete suppression of detectable viremia in many patients, viremia reemerges rapidly after interruption of treatment, consistent with the existence of a latent viral reservoir. This reservoir is thought to consist mainly of latently infected resting memory CD4+ T cells. Due to the long half-life of this reservoir (44 months), it has been estimated that its total eradication with current treatment would require over 60 years.
Latently infected cells contain replication-competent integrated HIV-1 genomes that are blocked at the transcriptional level, resulting in the absence of viral protein expression. HIV depends on both cellular and viral factors for efficient transcription of its genome, and the activity of the HIV promoter is tightly linked to the level of activation of its host cell.